Inductively coupled plasma (ICP) devices are widely applied in plasma etching processes. The working principle for plasma etching is as follows. The reaction gas is ionized under the excitation of the electric field so as to generate plasma, wherein the plasma contains active particles such as electrons, ions, as well as excited atoms, molecules, and free radicals. These active particles can react with the material layer to be etched, so as to pattern the material layer to be etched.
In inductively coupled plasma devices of the prior art, a non-uniform distribution of the electric field in the reaction chamber may cause plasmas in the reaction to be also in a non-uniform distribution, thereby influencing the uniformity of etching.